Benzochromene Derivatives for VA Mode Displays

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Liquid crystal displays using negative dielectric anisotropy media require compounds with high dielectric anisotropy and birefringence, but existing compounds often have high birefringence, which is not suitable for reflective displays like VA mode, and there is a need for substances with lower birefringence and improved stability against UV, heat, and electrical voltage.

Innovation Solution

Development of mesogenic benzochromene derivatives with specific structural modifications, such as trans-1,4-cyclohexylene and 1,4-phenylene residues, and naphthalene diyl groups, which provide negative dielectric anisotropy, broad nematic phase, and stability, while allowing for lower birefringence and improved solubility and optical anisotropy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If liquid crystal compounds with high birefringence are used to achieve negative dielectric anisotropy, then the dielectric anisotropy is improved, but the suitability for reflective displays deteriorates

Engineering Contradiction:

Improvedielectric anisotropyVSAvoidsuitability for reflective displays

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the molecular structure parameters of liquid crystal compounds by introducing specific mesogenic groups (benzochromene derivatives with trans-1,4-cyclohexylene and 1,4-phenylene residues) to achieve the desired balance of dielectric anisotropy and birefringence suitable for reflective displays

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates composite liquid crystal media by combining multiple compounds with different properties, including the newly developed benzochromene derivatives, to achieve the optimal combination of negative dielectric anisotropy and low birefringence for VA mode displays

Inventive Principle:

Principle #40Composite materials

2Reliability

If existing liquid crystal compounds are used, then the dielectric anisotropy is improved, but the stability against UV, heat, and electrical voltage deteriorates

Engineering Contradiction:

Improvedielectric anisotropyVSAvoidstability against UV, heat, and electrical voltage

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent modifies the chemical structure parameters of liquid crystal compounds by introducing stable mesogenic groups (benzochromene derivatives) that inherently provide better resistance to UV degradation, thermal stability, and electrical voltage stability while maintaining the required dielectric anisotropy

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces existing compounds with more stable benzochromene derivatives that have improved longevity and resistance to degradation, ensuring the liquid crystal display maintains its performance characteristics over extended operational periods

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If compounds with negative dielectric anisotropy are used in dielectrically positive liquid crystal media, then the dielectric constant perpendicular to the molecular axis is improved, but the complexity of the media composition increases

Engineering Contradiction:

Improvedielectric constant perpendicular to the molecular axisVSAvoidcomplexity of the media composition

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines compounds with negative dielectric anisotropy into dielectrically positive liquid crystal media mixtures, where the negative anisotropy compounds work synergistically with positive anisotropy compounds to achieve the required perpendicular dielectric constant while maintaining overall system functionality

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The benzochromene derivative compounds serve multiple functions simultaneously: they provide negative dielectric anisotropy, contribute to the overall dielectric constant, maintain liquid crystal phase behavior, and provide structural stability, thereby reducing the need for additional separate additives

Inventive Principle:

Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The mesogenic benzochromene derivatives achieve the necessary dielectric and optical properties, enabling efficient operation in liquid crystal displays with improved stability and reduced rotational viscosity, suitable for various display modes including VA mode.

Implementation Method 1

liquid crystal media with negative dielectric anisotropy (Δε)

Methodology Applied

Scientific EffectDielectric anisotropy: Dielectric Permittivity

Implementation Method 2

the liquid crystals are used as dielectrics whose optical properties change reversibly when an electrical voltage is applied

Methodology Applied

Scientific EffectElectro-optical effect: Electro-Optic Effects

Implementation Method 3

liquid crystal media with a large absolute value of the dielectric anisotropy

Methodology Applied

Scientific EffectBirefringence: Birefringence

Data Source

PatentEP1963298B1Benzochromene derivatives

Publication Date: 2011.11.02 MERCK PATENT GMBH

AI summary

The invention relates to benzochromene derivatives of formula (I), in which the various parameters are defined as cited in the text. The invention also relates to liquid crystal media containing said compounds, to the use of the media in electro-optic displays, in particular in VAN LCDs, and to the use of the compounds and their physiologically acceptable derivatives as therapeutic active substances.